Actuator control



April 1, 1947.

G. W. JACKSON ACTUATOR CONTROL 4 Filed March 14, 1.945

\ 60 66 5 is E 6| 3 Sheets-Sheet l ATTORNEYS April 1, 1947. G. w. JACKSON ACTUATOR GOXTROL Filed larch 14, 1945 3 SheetvSheet 2 me fi'figr way M ZQ ATTORNEYS Patented Apr. 1, 1947 ACTUATOR CONTROL George W. Jackson, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation oi. Delaware ation March 14, 1945, Serial N0. 582,771

16 Claims. 1

This invention relates to an improved control device for a reversible electric motor.

It is among the objects of the present invention to provide a control device for a reversible electric motor, operative to stop motor operation in either direction in accordance with the numv ber of revolutions of a. member driven by said motor. v

A further object of the provide a control device for an electric motor connected to a member adapted to be rotated a predetermined number of revolutions in either direction. said control device being operative by said member quickly to stop motor operation when the limit of rotations of said member in either direction is reached. v,

A still further objector the present invention is to provide an electric motor connected to a member for rotating it in either direction with a control device driven by said member and capable of being adjusted to stop motor operation in accordance with any predetermined equal number of revolutions of said member in either direction.

Further objects and advantages or the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred cembodiment of the present invention is clearly shown.

The above and other objects are accomplished by providing the electric motor with control mechanisms comprising limit switches connected lector type. As the motor driven member is illl= tated, the timing gears connected thereto will actuate the cams, one of which becomes effective to open its switch for stopping the motor when the member reaches its predetermined limit oi revolutions in this one direction. when the wo tor operates in the opposite direction, the open. switch will be permitted to close and after the member has been rotated the predetermined num ber of revolutions, the other cam will actuate its switch to open the circuit and stop motor opera tion in this direction.

' One gear of the train of gears between the motor-driven member and each switch operat ing cam is a single tooth gear operative intermi present invention is to (o1. ice-its) tently to engage and actuate the cam driving gear through portions of its complete revolution. This intermittent movement provides for quick.

rotation of the cam through each portion of its 5 revolution and especially through that portion in which it actuates its switch. Thus much greater sensitivity is obtained than would be available if conventional gears were used in which case very slow action would obtain. The single tooth gear is adjustable relatively to its respective cam gear, thereby rendering the device opezative in response to any desired number of revolutions oi the motor driven member.

In the present invention the motor is shown applied to an actuator which comprises a screw shaft, driven by the motor and having a nut thereon. The nut is arranged to have a load applied thereto which holds the nut non-rotatable and therefore longitudinally movable on the screw in res so to rototion thereof for moving the iced two extreme prcdetci mined In the draw gs Fig. l. is i through the cot Fig. 2 is e, wiring" not showing the various electrical units and their electrical connections,

view" taken rose section taken alon v it but taken alon oi the control mechin section, oi the it its box the box being iii). m Fig. 8 is a o mechanism shown in Fig. i.

Te ls". tenet view taken along the invention is shown 7 a a main housing 20 havhich recessed to of the s ally shaped i r 23. The no about the housing 24 is 433g housing housing ca one end t1. the other benches-erg edge lf=$tillg upon ststor housing 2 1 ective view of the coin-- lar bearing assembly 27 supported in a recess in the closed end wall of the motor housing 24.

Bearings and 21 rotatably support the shaft 28 of the motor armature 25. Suitable field or stator windings 39 are carried by the stator housing 22. The brushes of the motor are not shown, however, any suitable brush structure may be used.

The armature shaft 28 extends through the hearing 25 into the chamber formed inside the stator housing 22 between its partition 25 and the bottom wall of the recess in the end wall of the main housing 20. This end of the armature shaft 28 has the driving disc 32 secured thereto so as to rotate therewith. Disc 32 has annular flange 33 of lesser diameter than the inside diameter of the stator housing,

The bottom wall of the recess in the end wall iii of the main housing 20 is centrally apertured to receive the bearing assembly 35. One end of a stub shaft 36 is glournalled in bearing 35, the end of this stub shaft extending beyond the bearing having the armature disc 3! keyed thereto so said disc, when rotating, will rotate the stub shaft 36, but is movable longitudinally relatively thereto. Disc 31 is parallel and in closely spaced relation with the flange 33 of the driving disc 32.

is gr. M381 in diameter than flange 33 but" sli htly less than the inside diameter ofthe.

stator housing 22, thereby providing a. small air 1 gap for the passage of magnetic lines of force betwee.-. the disc 3? and stator housin 22. A magnet coil 35 is carried by a non-magnetic spool 39 surrounding the motor driven disc 32 and secured in the stator housing directly beheath the partition 25 therein.

The end of the stub shaft 36 to which the arms,- f ture disc 3? is slidably attached is centrally recessed. A headed screw 40 i threaded in a central opening in the bottom wall of the recess in the stub shaft,

cent the driving disc flange 33. An abutment the headed end of the screw being, substantially flush with the side of disc 31 adjasleeve 4! is provided in th recess of the stub.

shaft, said sleeve having an outwardly extendilange resting upon the bottom surface of a central recess in the armature disc 37, and an inwardly extending, annular flange at its oppo-' site end and normally spaced from the bottom of the recess in. the stub shaft. .& spring 42 surrounds the screw resting upon the on the abutment yieldably urges engagement with the brake ring 43 secured to the bottom wall of the recess housing so. I

The end of the stub shaft 36, opposite the end journalled in the bearing 35, is iournalled in the bearing 45. The intermediate portion 46 of the stub shaft between the two coaxial ends thereof, is eccentric to said end portions. Two bearing assemblies f? and 48 are carried by the eccentric portion 46 of the stub shaft 38. These earings 4? and 48 rotatably support a gear unit 53 providing the epicyclic gear unit 5 which is journalled in two bearings and 55 th main housing 20. These bear- 40, on end abutting against the bottom surface of the head of screw 40, the

lugs and gear unit 54 supported thereby are held in the main housing 20 by the retainer ring 51 hreadedly received in the open end of the main housing 20.

The gear unit 54 has an interiorly threaded,

central opening for receiving the threaded end of a tubular screw shaft 60. A pin 6!, passing through the gear unit 54 and screw shaft 60 assures secure attachment of said unit to said shaft. This end of the screw shaft 60 is recessed to receive and support the bearing in which one end of the stub shaft 36 is Journalled.

. Gear unit 54 has an outwardly extending, annular flange 58. On the annular, peripheral edge surface of the flange 58 a worm gear is provided having a gear tooth 59 of at least one and onehalf (1%) convolutions.

The outer surface of the, screw shaft 60 has a helical groove 6| extending from the threaded portion of the shaft to its opposite end. This groove 6| is substantially semi-circular in cross section.

A nut slldably fits about the shaft 40, the inner annular surface of the nut having a. helical groove 68 identical with and adapted to coincide with the annular groove 6| in the outer surface of the screw shaft so that these coinciding nut and shaft grooves form a round, helical channel between the contiguous surfaces of said nut and shaft.

In order mechanically to connect the nut to the Q shaft so that rotation of one relatively to the volutions of the round groove between the nut and shaft. This type of connection between I nut and shaft is detsiledly illustrated and described in the copending application of Calvin J. Werner, Serial No. 468,475, filed December 10, 1942, now Patent No. 2,383,901, and inasmuch as an ordinary thread connection between the nut and shaft would suffice as far as the features of the present invention is concerned, no further or detailed description of this portion of the I actuator will be made.

The out 80 has a tubular extension 44 secured thereto to which the load, to be raised and lowered by the actuator, is adapted to be attached.

.50 a A dust guard tube 80 is attached at one end to 1 the retainer ring 57 so as to surround the nut inwardly extending flange sleeve 4!. This spring 42 thus I the armature 31 into frictional in the end wall 2! of the v 45 and shaft 68. A dust seal 8| is carried by the nut and slidably engages the inner surface of the tube 00. v A

The gear unit 54 of the speed reducing gearing is utilized to drive the acuatlng mechanism of two limit switches which control the motor to' limit the range of movement of the nut 55 on the j screw shaft 60. The annular, peripheral surface of a flange 58 on said gear unit is provided with a worm gear tooth 59 having at least one and one I half convolutions. This worm gear 59 operatively engages a pinion I 00 rotatably supported on shaft m carried by the limit switch housing m which is attached to the actuator housing 25 in any suitable manner. V I

Two parallelly spaced brackets I II and 404 are attached in the housing In by their angular feet l0! and I06 respectively. The stub shaft "4,, vwhich carries the pinion I, is supported be-x tween two portions of brackets I03 and I44 which extend into an opening in the main actuator housing 2U."These brackets Inland, "4 are held u i in proper spaced relation by rigid spacer Posh 2c? of this switch is connected 2,41ass1 As the gear unit 54 is rotated, the worm gear 59 on the peripheral surface of flange 54 of said unit will rotate pinion Hill with which said worm gear meshes. Because of the relative sizes of worm gear 59 and pinion I00, and due to the fact that the screw on gear unit 54 is of such a low pitch, a comparatively large number of revolutions of the said gear unit 54 is necessary to rotate th pinion Hill a single revolution.

Pinion I03 meshes with and drives a gear I08 which is predeterminatcly larger than pinion I and thus a certain number of revolutions of pinion IE0 is necessary to rotate gear I08 one revolution. The single tooth gears III and III are secured to gear I08 and rotate in unison therewith. Each revolution oi. single tooth gears I I I and I I! will rotate their cooperating gears I40 and MI through an are equal to the distance of two of their teeth. The present Fig. '7 illustrates a mechanism where six revolutions of the single tooth gears are necessary to turn their respective cooperating gears one complete revolution.

The cams I33 and I34 are set in the present device so that one will actuate its respective limit switch to open the motor circuit when the nut 65 reaches a predetermined position on the screwshaft 60 adjacent the gear unit 54 and the other cam will open its switch when the nut reaches a position on the screw shaft adjacent its end op-.

postie gear unit 54. The movement of the nut from one to the other of these predetermined positions requires a certain number of revolutions of the shaft 5t inasmuch as gear unit 54 is directly attached to said shaft, it will rotate the same number of revolutions during this nut move? ment. Gearing including the worm screw 59, pinion I00, gear I08, single tooth gears HI and i I! and their cooperating gears I and I 4| are so l signed and constructed that the revolutions of the screw shaft and its gear unit 54, necessery to move the nutirom one selected position to another, Will actuate the cams I33 and I34 so that one will actuate its switch to open the motor circuit when the nut reaches one of its selected positions while the other cam operates its switch to open themotor circuit when the nut reaches the other of its selected positions. The opening of the motor circuit stops motor operation which causes shaft rotation to cease, thus stopping the linear movement of the nut at the selected position, while the closing of its gap in the motor circuit by the other switch prepares contact 2) to bridge and connect stationary contacts 2| l and H2. Contact 2| 2 is connected to one end of the motor field winding 300, the other end 01 which is connected to the one side of the armature 29 and also with one end of the electromagnetic clutch winding 30, both opposite sides of the armature and winding 38 being grounded.

Stationary contact 2 of contactor 209 is connected with the wire 205 leading to the battery 200 through the master switch "I.

The stationary contact 204 of the selector switch, engageable by the manually operable contact member 202 or said selector switch, is connected with the one contact M5 0! the limit switch I38. The contact 2I8 cooperating with contact M5, is connected with one side of the magnet winding 2!! of'the contactor 2:0, the other side of said winding being grounded. This contactor 2I9 has two movable bridging contacts 220 and 22 I adapted to be actuated to bridge and connect stationary contacts 222-222 and 224-425 respectively when the winding 2" is energized. Stationary contact 222 is connected to one end of the motor field winding 30b, the other end of said field winding being connected to stationary contact 225 and also to the arms ture 23 and electromagnetic clutch winding 20. Contact 224 is connected to the power line 205 and contact 223 is grounded.

Fig. 2 shows the control com I" so positioned that it engages with the operating member of limit'switch I30, thereby causing the contacts 206 and 201 or this switch to be separated and maintain open'its gap in the control circuit oi the motor. The control cam I34 0! switch III, on the other hand, is so positioned that it is disengaged from the operating member or this switch permitting the contacts 2!!! and H8 to remain closed and eflect motor operation in the one direction. The manually operable contact 202 of the selector switch and the master switch 20I are as it operates to cause the circuit for the following cycle of motor oD- eration during which the motor will turn the,

shaft in the reverse direction to cause the nutto move toward the other selected position.

In Fig. 2, the electric motor armature and field windings 39a and 30b are shown. The

shown completely open, so that, as shown, the motor cannot iunction. V v

To coincide Figs. 1 and 2, it must be assumed that limit switch I20 controls the electric motor the nut 00 to move upwardly on the screw shaft 80 for with the nut in its extreme up positio as shown in Fig. 1, the switch I38 will have been actuated to open the motor control circuit to stop motor operation, while the limit switch II! will have been closed to prepare the motor control circuit for the next nut descending rotation or the motor.

If, for purposes of description. the actuator of the present invention is'used to open and close a cowling flap in arr-airplane, the position of the nut in Fig. 1' would maintain the flap closed.

source or? electric power is shown to be a hatitem 208, one side grounded, the other side connected to the master switch 20L Switch 2M is also connected to the manually operable contact member 282 of a selector switch which has stationary contacts 2G3 and 204 with which said contact member 202 may selectively be engaged, one to cause the motor to rotate in one direction, the other to cause the motor to operate in the opposite direction. switch 2M with member 202. Contact 263 is connected to one contact 298 of one limit switch, for instance, I3'i, while the cooperating contact Wire 205 connects to the magnet To open the flap, the motor is operated to rotate the screw shaft 60 in the direction in which the nut would move downwardly on the shaft and thus open the flap. When the nut has reached a predetermined position in this directional movement. the flap would be wide open and the motor would be stopped automatically. To eflect this, with the various elements of the device in positions as shown in Figs. 1 and 2 particularly, the operator closes the master switch 2H) and then shifts the manually operable contact 202 into engagement with stationary contact 204. This switch I31 thence through the magnet winding ll! of contactor 2!! back to the battery via. the

ground connections. Nowwlnding III is onergized to actuate the movable contacts 200 and 2 into bridging connections with their respective stationary contacts 22 2-223 and 224-225. Current from the power line 205 may now flow to contact 224, across the bridging contact Hi to contact 225 thence to juncture 226 where a split circuit is directed, one through field winding 30b to contact 222, bridge 220, contact 223 to ground, the other from 228 through the motor armature 29 and the electromagnetic clutch winding 38 to ground. With these circuits completed, the motor will rotate in one direction, the electromagnetic clutch will connect the motor with the speed reducing gearing connected to screw shaft 80 and the nut 85, attached to the flap by member 60, will move downwardly on said shaft to open the flap. As the speed reducing gearing operates to transmit the rotation of the motor to the shaft, the gear unit 54 of said gearing rotates the pinion I and pinion I00 will, through the interme- Ill-l l1,

diate gearing including gears I08, c m, cause rotation of the control cams I33 and I34 at a definite relative speed.

, At a predetermined time during the downward movement of the nut 65 or more specifically, after a predetermined number of revolutions of gear tact with terminal 204 and must be moved into enga ement with contact terminal 203 to render switch I38 eifective to complete motor circuits.

When the speed reducing gearing and particularly the gear unit 54 thereof has been rotated Closing of 10 switches "on and oil may be obtained at an desirable point in the movement of the nut on the screw shaft. The mechanism may be set to operate the limit switches after the nut has moved a considerable distance on a screw shaft and again said mechanism may be readJusted easily and without much trouble to operate the limit switches after the nut has moved only a slight distance in either direction on a screw shaft.

The mechanism is sturdy and positive, assuring safe and reliant control and it is of simple design requiring only a, screw driver to loosen two members for permitting adjustments to be made.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow;

- What is claimed is as follows:

1. In combination with a prime mover capable of operating in opposite directions, of a movable member operated thereby; a unitary device for controlling the operation or the prime mover in accordance with the movements of the movable member, said device comprising a pair or control members each operative to control the operation of the prime mover in a respective direction, a

separate actuatorfor each control member; andv a train of, reduciion gearing for driving said actuators, said gearing being connectible with the single tooth gear secured to each side of the the necessary number of revolutions to cause the nut 85 on shaft to move from its extreme up position to its selected down position in which the flap is fully open, the gee ring interconnecting gear unit 54 with cam I34 will have moved said cam so that it w ll engage and actuate the operating member of its limit switch I31 and thus open con-f tacts 2| 5 and 2l8 of said switch thereby breaking and circuit through the contactor magnet winding 2, deenergizing it and causing the lector switch need not be touched for under these circumstances no circuit is established. However, as soon as the contact 202 of the selector switch is moved into en agement" w th terminal contact 202 and switch20l is closed, then, by virtue o! the now closed limit switch I38, contactor 209 is rendered effective toestablish motor circuits includ ing 'fleld winding 30a which resultfiinrotat on of the motor to turn shaft 80 so that the nut there again be opened to stop motor operation;

movement. -By varying the relative positions of I the cum to each other-land to the single tooth gears which actuate them, operation of the intermediate gear, each single tooth gear being operative oncein each revolution togengage and operates. gear attached to a respective actuator,

to rotate said actuator a portion ofa revolution. 2. In combination with a reversible electric motor, of a member rotated thereby: a housing; a

' unitary device in said housing for controlling the motor'in accordance with the revolutions of the rotated member, said device comprising a pair of switches eachoperative to stop motor operation (in one direction respectively; an actuator for each switch; anda plurality of cooperating reduction gears'one ofwhich is operatively connected to therotated member so as to be driven thereby and has a single tooth gear adjustablyattached to I; each side thereofreachsingle tooth gear opera- .tiveiy' engaging' a" gear secured to an actuator for operating it through a portion oi arevolution for each complete revolution of the single tooth gear. I 3, In combination with a reversible electric motor, or a member rotated thereby; a housing; a

unitary devicein said housing for controlling the motor in accordance with" therevolutions of the rotated member, said device comprising a pair of switches each operative to stop motor operation in one direction respectively; an actuator for each switch; and a plurality of cooperating re- ,duction gears'comprising a main gear; a gear on will again move upwardly to close the flap; connecting themairi gear to the rotated member; During this movement, switch 131 will be closed and at a predetermined time, switch I" will I a single tooth gear adjustablyattached to each side ofthe main gear, and a gear secured to each actuator and engaged by a single tooth gear dur- "ing each revolution thereof, first to rotate the actuator gear through a predetermined portion of a complete revolution and then to lock said actuator gear against rotation.

4. In combination with a reversible electric mOtOIZOf a member rotated thereby; a housing: 25 aunitary device in said housing for controlling the motor in accordance with the revolutions of the rotated member, said device comprising a pair of switches each operative to stop motor operation in one direction respectively; an actuator for each switch; and a plurality of cooperating reduction gears comprising a main gear, an intermediate gear connecting the main gear to the rotated member; a gear attached to each switch actuator; and a disc adjustably secured to each side of the main gear, each disc having a single tooth provided on its annular edge, said tooth operatively engaging and rotating a respective actuator gear through a predetermined portion of its complete revolution while said disc is rotating through one part or a revolution, the annular edge of the disc engaging two teeth of the actuator gear to lock it against rotation while the disc rotates through the remaining portion of its revolution. 5. In a device of the character described, the combination with a reversible electric motor; of rotatable screw shaft having a non-rotatable nut threadedly supported thereon; means comprising an electromagnetic clutch. and planetary gearing operative to connect the motor with the screw shaft; a switch operative to control the direction of motor rotation; two limit switches, each operative to effect starting and stopping of the motor in one direction respectively; and automatic means operative to actuate the limit switches in accordance with the direction and nmnber of revolutions of the screw shaft, said means being driven by one of the planetary gears connecting the electric motor and screw shaft.

6. In a device of the character described, the combination with a reversible electric motor; of. a rotatable screw shaft; a nut threadedly supported on the screw shaft and arranged against rotation: mechanism comprising electromagnetic clutch and planetary gearing operative to coniiect the motor with the screw shaft; a switch operative into one position or another to effect motor operation in one direction or another respectively; two limit switches, each operative to effect starting and stopping of motor operation one direction respectively; and means automatically operative to actuate said limit switches in accordance with selected number of revolutions of the screw shaft in one direction or the other, said means being driven by one of the planetary gears connecting the motor and screw shaft and comprising cams for actuating the limit switches and intermediate driving gearing including lost motion gears adjustablv maintained in driving positions to their cooperating gears.

t. In a device of the character described, the

combination with a reversible electric motor; of

a screw shaft; a nut threadedly supported on the screw shaft and arranged against rotation; mechanism operative to connect the motor with the screw shaft; a switch operative into one position or another to effect motor operation in one direction or another respectively; two limitswitches, each operative to effect starting and stopping of motor operation in one direction respectively; and means automatically operative to actuate said limit switches in accordance with selected positions of the nut on the screw shaft, said means being driven by the mechanism connecting the motor and screw shaft and compriscams for actuating the limit switches and cooperating gears for rotating the cams, said gears including two, single tooth gears, each adjnstably secured to a driving gear and operathereby to engage a cam timing gear, ad- ,lllstmfint of said single tooth gears relative to 12 the driving gear varying the effective time or the cams relatively to positions of the nut on the screw shaft.

8. In a device of the character described, the combination with a rotatable screw shaft threadedly supporting a non-rotatable nut; a prime mover for driving said screw shaft; planetary gearing connected to the screw shaft; an electromagnetic clutch energizable to connect the prime mover to the gearing: a device for controlling the magnetic clutch and the prime mover and eflecting the operation of the prime mover in one direction or the other; and means for operating the control device to stop operation of the prime mover in one direction or the other as the nut reaches predetedmined positions on the screw shaft, said operating means comprising a, pinion operatively connected to one of the planetary gears so as to be rotated thereby, a gear driven by the pinion, a single tooth gear at vtacheci to and rotatable by the last mentioned gear, and another gear, operatively attached to the control device, engageable by the single tooth gear and rotated a fraction of a complete revolution for each complete revolution 01' the single tooth gear whereby the control device is rendered eflective to deenergize the magnetic clutch and stop prime mover operation after a predetermined number of revolutions oi the screw shaft in one direction or the other.

9. In a device or the character described, the combination with a rotatable screw shaft having a non-rotatable nut; planetary gearing connected to the screw shaft; a prime mover for driv. ing said screw shait in either direction; a magnetic clutch energizable to connect the prime mover to the planetary gearing; a control device for effecting energization of the magnetic clutch and operation of the prime mover in one direction or the other, said device comprising a manuallyoperable member to control directionaloporation oi the prime mover and two separate members each operative to effect stopping of the prime mover; and means for operating said two separate members of the control device in timed relation to the position of the nut on the screw shaft, said means comprising a pinion driven by one of the planetary gears, a gear rotated by the pinion; a single tooth gear attached to the last mentioned gear so as to rotate therewith; and a final gear operatively connected to the two separate control members to actuate them, said final gear being engaged and rotated through a traction of its complete revolution by a complete revolution oi the single tooth gear, whereby one of the separate control members is actuated to stop prime mover operation in one direction and the other member to prepare a circuit for prime mover operation in the opposite direction.

10. In a device 01 the character described, the combination with a screw shaft threadedly sup porting a non-rotatable nut; a, reversible electric motor for driving said shaft; switches for controlling motor operation; and mechanism driven by the motor for actuating one or the other of said switches to stop motor operation when the shaft has rotated to move the nut into a predetermined position adjacent one or the other end or the shaft respectively, said mechanism comprising a pinion operatively connected to the screw shaft so as to be rotated thereby. a single gear mounted on a stub shaft and meshing with the pinion; a single tooth gear adjustably mounted on said stub shaft on each side of the single gear, a second stub shalt having a. switch oper- 13 ating cam attached to each end thereof, and two gears attached to said second stub shaft, each of these last mentioned gears being engageable by the single tooth gear, once in each complete revolution thereof and turned through a fraction of a complete revolution in response to a complete revolution of the single tooth gear.

ll. In a device of the character described, the combination with a screw shaft threadedly supporting a nut adapted to be secured to a nonrotatable element; a reversible electric motor for rotating the screw shaft; electric switches for controlling motoroperation; and mechanism for operating said switches in timed relation with the position of the nut on the screw shaft, said mechanism comprising a pinion operatively connected he screw shaft so as to driven thereby, a

aratively larger gear meshing with the pinand having a split stub shaft extending from each side thereof, a sleeve on each stub shaft, adjustable relatively thereto, a wedge screw in each split shaft for expanding the shaft to secure the sleeve thereon adjusted position, a single tooth gear secured to each sleeve so as to be rotatable with the first mentioned gear, a cam shaft having a switch operating cam at each end thereof for engaging and operating ti separate motor control switches, and a final p r of seemed to the camshaft, each of d pair of gears heing engageahle by a respectwo single tooth gear once in each complete revo lotion thereof to rotate the cam shaft through a predetermined fraction of its complete rev01ution in response thereof.

In a device of the character described, the combination with a screw shaft; a nut threaded on the screw shaft; a reversible electric motor cw shaft to cause the nut to con; switches for stop- Men the nut on th screw i switches operly timed relation, to the the screw shaft, said mechin driven by the motor, eshing with the pinion, a ash side of the intermecured coaxialiy thereto and having a notch on, each side of said single i ring a switch actuating cam is end thereof, said cams havr so that the switches cpr concurrently open or cam sh t, each adapted to be engaged operatively by a respective single tooth gear and operthrough a fraction of a complete revolution by revolution of the respective single tooth the adjacent pairs of teeth of said cam shaft gears being circularly cohcaved to provide a circularly shaped surface of slightly a screw shaft having a nut threadedly supported thereon; of a casing for housing said shaft and its driving motor; and a box attachable to said casing, said box containing mechanism for controlling the shaft driving motor in accordance with the position of the nut on said screw shaft, said mechanism comprising a pinion supported by the box and operatively connected to the screw shaft when the box is attached to the casing, a single gear in the box meshing with said pinion, a single tooth gear adjustably and coaxially secured thereto on each side thereof, a cam shaft, a cam at each end of the cam shaft; two gears attached to the cam shaft each adapted to be engaged and operated through a predetermined portion of a complete revolution by a single tooth gear during each complete revolution thereof; and switches in the box engaged and operated by the cams respectively to stop motor operation in accordance with a predetermined number of screw shaft rotations in one direction or the other respectively.

14. In a device of the character described, the combination with a screw shaft threadedly supporting a non-rotatable nut; of a prime mover capable. of operating in two directions; means operative to connect the prime mover with the shaft to effect operation of the shaft in two directions; a control device for the prime mover; said mechanism operative to actuate the control device for stopping the prime mover in accorclance with the position of the nut on the shaft, said mechanism comprising a cam operative to engage and operate the control device at one time wh n said cam moves in one direction and at another time when said cam moves in the other direction, and cooperating gearing connecting the cam with the screw shaft, said cooperating gear ing having a lost motion gear adjustahly secured toits driving gear and once in each revolution thereof, to engage and operatethe gear directly connected to the cam through a predetermined arc of its complete cycle of rotation.

greater radius than the radius of the untoothed not engaged the single teeth of the single teeth gear.

iii, in a device oil the character described, the combination with a reversible motor for driving 15. In a device of the character described, the combination with a reversible electric motor; of a screw shaft; a nut threadedly supported on the screw shaft and arranged against rotation; mechanism operative to connect the motor with the screw shaft; a switch operative into one nosition or another to effect motor operation in one direction or another respectively; two limit switches, each operative to effect starting and stopping of. motor operation in one direction ro spectively; and means automatically operative to actuate said limit switches in accordance with selected positions of the not on the screw shaft, said means being driven by the mechanism connecting the motor and screw shaft and comprising two cams, one for operating each limit switch and cooperating gears, one of which has a stub shaft extending from each side thereof and upon each of which a single tooth gear is adjustable attached, said single tooth gears each bein op erated by the supporting gear to engage and actuate a cam rotating gear, alteration in the relative position of a single tooth gear on the supporting gear varying the operation of a re spective limit switch relative to the position of the nut on the screw shaft.

16. In a device of the character described, combination with a reversible electric motor; source of electric power; of a rotatable shaft driven by the motor: a selector switch mov able into one or the other of two positions for selecting direction of motor operation; two con trol switches each adapted when closed and the selector switch is in proper position, to be connected in circuit with a source of power for rendering the motor operative in a certain direction, and when opened, to stop motor operation; and means driven by the screw shaft for actuation of the two control switches to open or close their respective circuits in accordance with the direction and number of revolutions of the screw shaft, said means comprising a pair of control members each operative to control the operation of the prime mover in a respective direction, a separate actuator for each control member; and a train 01 reduction gearing for driving said actuators, said.

gearing being connectible with the movable member so as to be driven thereby and comprisin: a connecting gear, an intermediate gear, a gear attached to each actuator, and a single tooth 16 gear secured to each side or the intermediate gear, each single tooth gear being operative once in each revolution to engage and operate a gear attached to a respective actuator, to rotate said 5 actuator a portion of a revolution.

GEORGE W, JACKSON.

REFERENCES CITED The following references are 0! record in the me oi this patent:

UNITED STATES PATEN'I'S Certificate of Correction Patent No. 2,418,351. April 1, 1947;

GEORGE W. JACKSON It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 9, line 49, for and before circuit read the; column 14, line 30, claim 14, for said before mechanism read and; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 22nd day of July, A. D. 1947.

LESLIE FRAZER,

First Assistant Commissioner of Patents.

Certificate of Correction Patent No. 2,418,351. April 1, 1947;

GEORGE W. JACKSON It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 9, line 49, for and" before circuit read the; column 14, line 30, claim 14, for said before mechanism read and and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 22nd day of July, A. D. 1947.

LESLIE FRAZER,

First Assistant Commissioner of Patents. 

